I’d be very very careful. Possibly worth wearing a full face helmet and some pads as going to a smaller wheel size will defiantly make rolling over small trail obstacles far far more difficult for you and the bike, especially if you’ve got used to 29er wheels and have forgotten the art of ” getting over small trail obstacles” since going from (I assume) 26″ wheels to 29″ wheels, you know, that sort of pulling motion on the bars coupled with a 1/4 of a pedal turn to unweighted the front wheel quickly followed by throwing your body slightly up and forwards to give the rear wheel chance to clear said obstacle.
If you can’t do that any more, because, let’s face it, you don’t need to on a 29er as they roll over things better of course, (we all know that because magazine adverts and journalists told us) then I’d even consider specialist insurance. Let them know that you will be riding a far less capable bike though, even though the premium will shoot up.